Adjustable triangle



y 1950 K. J. DE JUHASZ 2,515,761

ADJUSTABLE TRIANGLE Filed Jan. 17, 1947 Fig.1. Z.

WITNESS:

INVENTOR.

Patented July 1 8, 195i) V 4 I I I UNITED STATES PATENT OFFICE Y Y -;2,515,7c1

V ADJUSTABLE TRI An LE Kalman "John 1 De J uhas' z", State College, Pa. Application January 17, 1947.,Jseria1 .No. 722,683 4 Claims. (01. es-93') My invention relates to improvements "in an hounded by straight ruling edges and a circular adjustable triangle for use by draftsmeh, co'mare as shown. The circular portion of both prising two-pivotally connected bladesbounded blades'is of reduced thickness, in our example by-straightruling edges which can be adjusted to about 1% inch, .inyirtue of which the two blades a desired angular relationship to one another, {5 l...an,d .2 can be assembled together forming a one of said blades carrying a degree graduation structure of flginch thickness, andpan berotated and the other an index markor a Vernier for the relativelyto each other about the center of said setting of the desired angle. .circularportion and thereby the relative angular Adjustable trianglesof this general type have position of the several ruling .edgescan be set to been knownand'used for a long time, but existing the .desiredvalue. One of the said blades e. g,,

executions have the disadvantage that they incorblade ,I is marked with a degree graduation ,la porate protruding knobs and other raised portions and the other, e. ;g., blade .2 carries. an index onone side, as a consequence-of which such trimark 12d. Asshown in .Eig. .1 the degree,mark .on angles can belaid flat only on its one side on the, gender coinoidingewith the index mark on blade drafting board. r 15 '2 xp es the angl between the ruling edges 1c "The main objective of my'invention is to elimand .20; from wthisreading the anglesformed by inate knobs and raised portions protruding bethe other straightedges of the twoblades loan y'ond the thickness of the blades, in virtue of be'toundbysimple mentalcalculation. "For more which my adjustable triangle can be laid flat on accurate setting of. the anglefit .is possible, or the drafting'board on- -both of its sides, whereby 2 course, tense on blade .2 a .vern'ier scale instead thelaying'out of lines symmetrically to acertain of the index mark 17 1 ina manner ,well knownin symmetry "axis is facilitated. Further advansurveying, .toolmaking andother protractor ,intages of my inventionare:-*fewness of parts, and .struments.

simplicityo'f-fparts, as a onsequence of which it In order to hold the blades ,1: ands a isadapted for accurate and inexpensive manu- '2 getherthe oircularportions,ofthetwobladesare facture. .formed withla'large .cireu-larhore concentric with I attain these objectives and advantages by the thecircular portion, the periphery of which cirrconstruction, illustrated in the "accompanying xcular boreis 'Lchamfered. about .45 degrees, or

drawings, in which: counterbored. .to' form shoulders, .and this circu- Figure l isaplan view of a preferred execution flarlbore engages with the correspondingly beveled of my adjustable triangle containing rigidly inor shouldered outside-periphery of ,theclamp corporated angles of 90, and 3.0 degrees; .3 whichis .insertedinto the circular bore witha Figure 2511s "a cross'sectional vi ew takenalong tradial tension. Thenclampring .3 .is preferably line 2-2 showing the pivot construction; .made .of steel orpther metalor.materialothigh Figure 3 is a plan view of another pivbt Icon .elasticity ;f.-it is. similar .to .asplitringor retaining struction; v ring usedinrmachine construction, and is formed Figure 4 is 'a rsec'tional view .of the pivot con- .preferablyas a body .of..equal.strength in order struction shown in Fig. 3,.taken along line '.44,; to produce-an approximately uniform radial FigureFi-is the plan viewflof another modificaforce along its entire peripheral length. .lnflvirition of the pivot construction; Q, Q 1 l .rc tue of. its .lradial tension .thelbeyeled periphery of t Figure dis a sectional View .of the pivotconolampringlfi .tendstto.urgethetwgbladies-l and struction shown in Fig. 5, taken along line 6-6; 2 together .producinga zsmoothlfriction between Figure 7 is the plan View of a modified executhe contacting surfacesgoflblades land 2. .,I=.hay e tion of my adjustable triangle containing rigidly found that by making the clamp ring of sufficient incorporated angles of 90, 45 and 22% degrees; 45 stifiness the resulting friction is fully satisfacand tory for drafting purposes, and the two blades I Figure 8 is the plan View of another modificaand 2 will retain their set angular relationship tion of my'adjustable triangle containing rigidly without any additional locking means, until the incorporated angles of 45 and 30 degrees. angular relationship of the two blades I and 2 Referring to Fig. l the two blades 1 and 2 are is changed intentionally by manual force.

preferably made of transparent plastic material I have, however, invented a locking mechanism such as the well known Lucite, or Plexiglass, but in case an additional security against unintended can be made also of metal if absolute freedom slippage is desired, e. g., for tool or template layfrom warping or other secular. changes is desired; out purposes. One form of this locking mechthese have a thickness of about inch and are anism is shown in Figs. 3 and 4 and consists essentially of a modification of the clamp ring 4 the two ends of which form the jaws 5 and 6 engaging with the cam I fitted with the handle 8 by means of which the cam I can be rotated with the thumb or finger. Thereby the two ends of the clamp ring 4 can be forced apart to produce a gripping action on the beveled periphery of the circular bores in the two blades I and 2. The cam is fitted into the space between the two jaws 5 and 6 by means of a recess in the jaws which prevents the cam fromfalling out sideways. It will be realized that after the cam 1 is inserted between the jaws 5 and 6, and the handle 8 is.

other means of forcing apart the two ends of the clamp ring 4 may be employed, as by wedges,

spiral cams or their combinations.

I have found p'racticalalso another modification of the pivot construction, shown in Figs. 5

and 6 in which a'clamp ring 9 is provided between the two blades I and 2 and the spreading ring II]. This clamp ring 9 is made of some soft material such as aluminum or plastic, exerting little radial force, the radial force being provided mainly by the spreading ring Ill, which said spreading ring l can be made ofsteel wire of round or rectangular cross section, or stamped out of fiat strip steel. In Figs. and 6 a spreading ring of round wire is shown. The advantage of this construction is that the clamp ring 9 can be made of such material which wears more than .the two blades l and 2, and thereby the wear on the more expensive blades is reduced and the useful life of the instrument is increased. It will be realized that a locking'mechanism of the type shown in Figs. 3 and 4 can be incorporated also in this modification of the pivot.v

, Fig. 7 shows a modified form of the blades II and I2, in which the rigidly incorporated angles are 90,- 45 and 22 /2 degrees; This gives, for a given size instrument longer ruling edges I la and 12a as compared with the form shown in Fig. 1, at a sacrifice of the rigid angle of 30 degrees,

which is not present in this case.

Fig. 8 shows another modification of the blade form, in which the two blades I3 and [4 are of identical form which is an advantage from the production point of view, and which also permits a greater total range of rotation. This advantage, however, involves the sacrifice of the 90 degree angle, and some reduction in the rigidity of the instrument.

1. In an adjustable triangle comprising two blades of the same thickness, each blade havin a circular portion, said circular portion of said blades being reduced to about one-half of the blade thickness, the said circular portions of said blades fitting into each other and rotatably pivoted to each other to permit setting of said two blades to the desired angle, concentric bores formed in the circular portions of said blades, said concentric bores having chamfered edges, a radially expansible clamp ring having its outside periphery beveled towards the center of the ring to fit said chamfered edges of said bores formed in said blades to produce an axial force for urging the two blades into close mutual contact, when said ring is expanded substantially as described.

2. In an adjustable triangle comprising two blades of the same thickness, each blade having a circular portion, said circular portion of said blades being reduced to about one-half of the blade thickness, the said circular portions of said blades fitting into each other and rotatably pivoted to each other to permit setting of said two blades to the desired angle, concentric bores formed in the circular portions of said blades, said concentric bores having chamfered edges, a radially expansible clamp ring having its outside periphery beveled towards the center of the ring to fit over the chamfered edges of said concentric bores formed in said blades said clamp ring having its inside periphery grooved, and a spreadingring engaging said grooved inside periphery of said clamp ring for expanding said clamp ring.

3. In an adjustable triangle as claimed in claim 1 said ring having a break therein providing ring ends, and means for forcing the two ends of said clamp ring apart to produce a locking action.

4. In an adjustable triangle as claimed in claim 1 said ring having a break therein providing ring ends, anda cam engaging with the two ends of said clamp ring for forcing the two ends of said clamp ring apart to produce a locking action.

KALMAN JOHN DE JUHASZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

